Network communication system with node energy reduction packet protocol

ABSTRACT

A method of communicating a packet between a first node and a second node, the packet comprising a data payload and a portion of information preceding the data payload. The method comprises: (i) first, identifying a quality of a channel between the first node and the second node; (ii) second, in response to the quality of the channel, selecting a manner of communication of the information preceding the data payload; (iii) third, encoding the selected manner of communication in the portion of information preceding data payload; and (iv) fourth, transmitting the packet from the first node to the second node.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/953,683 filed on Nov. 30, 2015, which claims priority to U.S.Provisional Patent Application 62/158,307, filed May 7, 2015, which areincorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

The preferred embodiments relate to network communication systems andmore particularly to energy reduction in system nodes.

Various wireless and wireline networks have different nodes thatcommunicate with one another via a network, including example networkssuch as point-to-point networks and mesh networks. In either example,one node in a network communicates with another node. For thepoint-to-point descriptor, however, generally a first node communicatesdirectly with a second node, where the second node is the final intendedrecipient of the communication. For the mesh descriptor, however, afirst node may communicate to a second node, which is along the way ofone or many nodes that pass along a communication to ultimately reach adestination node that is the final intended recipient of thecommunication; such passing along is sometimes referred to as hoppingand the network a multi-hop network. In any event, such communicationsare in contrast to multipoint (or broadcast), where a transmitting nodecommunicates simultaneously to multiple different nodes.

Network nodes are now being implemented in numerous forms ofsensors/controllers that typically communicate data about some relatedapparatus and my provide control to that apparatus. For example, narrowband power line communication (PLC) is a low data rate (5 kb/s to 1024kb/s), communication technology that is specifically designed to be usedin smart utility metering applications, automated meter reading,renewable energy communications, lighting control, and communicationbetween electric vehicle and electric vehicle service equipment, amongother applications. As another example, IEEE 802.15.4g pertains to thecommunications technology used in Smart Utility Networks (SUN) forwireless media, and this acts as a complement to the wired NB-PLCtechnology for Smart Grid communications. As still another example, theInternet Of Things is a developing technology where communication nodeslook to be implemented into myriad different applications for purposesof data gathering and device control. Certain of the nodes in these andother applications are, or will be, powered by small batteries and, assuch, an ongoing goal is to minimize power consumption so as to sustainthe operation of the node as long as possible without requiring thebattery to be changed. Thus, various efforts are made in the industry,including in hardware, software, and the like, toward the goal of powerefficiency. The preferred embodiments also endeavor to improve the priorart in this regard, as are further detailed below.

BRIEF SUMMARY OF THE INVENTION

In a preferred embodiment, there is a method of communicating a packetbetween a first node and a second node, the packet comprising a datapayload and a portion of information preceding the data payload. Themethod comprises: (i) first, identifying a quality of a channel betweenthe first node and the second node; (ii) second, in response to thequality of the channel, selecting a manner of communication of theinformation preceding the data payload; (iii) third, encoding theselected manner of communication in the portion of information precedingthe data payload; and (iv) fourth, transmitting the packet from thefirst node to the second node.

Numerous other inventive aspects and preferred embodiments are alsodisclosed and claimed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 illustrates a block diagram of network nodes as part of acommunications system.

FIG. 2 illustrates a general form of such a packet PT, including apreamble PR, followed by a header HD, followed by a data payload PD.

FIG. 3 illustrates an example of a communication packet PT_(PLC) forG3-PLC.

FIG. 4 illustrates a flowchart of a preferred embodiment communicationmethod for one or more of the nodes N_(x) from FIG. 1.

FIG. 5 illustrates an example of an alternative preferred embodiment andenergy reducing communication packet PT′_(PLC) for G3-PLC.

FIG. 6 illustrates a partial flowchart of another preferred embodimentcommunication method 100′, as a modification of method 100 of FIG. 4.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 illustrates a block diagram of network nodes N₁ and N₂ as part ofa network communications system 10, which is known in the art and isfurther improved upon per the preferred embodiments. Each of the nodesN_(x) in system 10 may represent various devices, and will be understoodto include sufficient hardware and/or software to perform thecommunication functionality described in this document, where suchhardware and software are readily ascertainable by one skilled in theart. For example, each of the nodes N_(x) in system 10 typicallyincludes a communication interface (e.g., RF transceiver; analog/digitalfront end), processing circuitry, memory or hardcoded programming space,and input/output functionality. In addition, each of the nodes N_(x) insystem 10 may include additional functionality, such as in connectionwith data sensing/gathering and device control, typically at a locationwhere the node N_(x) is located. Still further, in some preferredembodiments, each of the nodes N_(x) is battery operated, so thatreducing power consumption so as to increase the time needed betweenbattery changes is critical, based on considerations including cost,access, viability, and the like.

Nodes N₁ and N₂ communicate bi-directionally with each other, as showngenerally via communication paths CP_(1.2) and CP_(2.1). Communicationpaths CP_(1.2) and CP_(2.1) may be via a wire (not shown) or wirelesslysuch as through radio frequency transceivers, and the path traveled bysuch communications is typically referred to as the channel. Moreover,by various different communication standards or protocols, typicallyeach communication is by way of a set of information typically referredto as a packet, although in some standards or conventions a packet alsomay be referred to as a frame. For purposes of the preferred embodiment,a general form of such a packet PT is shown in FIG. 2, and it includes apreamble PR, followed by a header HD, followed by a data payload PD.Other information also may be included, but these three aspects sufficefor demonstrating the inventive scope. In general, the preamble PR is atype of introduction that indicates the beginning of the packet, wherebyanother node(s) in system 10 may monitor for and detect the packetpresence, and potentially synchronize with it, by having detected itspreamble. In general, the header HD precedes the data payload DP andcontains other information so that the data payload DP can be properlycomprehended by a receiving node, so for example the header HD mayindicate how much information will be contained in the data payload DPas well as addressing information so that the packet PT reaches theproper destination node. Finally, the data payload DP includes theactual data (e.g., sensed or collected information; control information)intended by the sending node to reach a destination node, where suchinformation was typically originally analog or digital information that,for efficiency of transmission, has been mapped to some type ofconstellation by way of a modulation scheme, where such schemes mayinclude, by ways of example, phase shift keying (PSK), such as two pointbinary (BPSK), four point quadrature (QPSK), or eight point quadrature(8PSK).

FIG. 1 also illustrates a node N₃, which likewise may communicatedirectly with node N₂ via communication paths CP_(2.3) and CP_(3.2);moreover, node N₃ may communicate with node N₁, with node N₂ acting asan intermediate node that receives such communications and forwardsthem, as between nodes N₁ and N₃. To simplify the illustration,therefore, only three nodes are explicitly shown in FIG. 1, but anadditional node N_(n) is shown to demonstrate, as one skilled in the artwill readily understand, that common networks can include asignificantly large number of nodes.

In system 10, the preferred embodiments endeavor to improve powerconsumption by each node in connection with its communications ofpackets. Such a goal may be understood with respect to the energyrequired for a successful communication between nodes, where such energyinvolves the energy required of the transmitting node and the energyrequired of the receiving node, where the former modulates, encodes andtransmits the packet, and the latter receives, detects, partially orfully decodes (depending on whether it is the final destination node),and returns some form of response to the transmitting node, where aminimum such response typically involves some type of acknowledgment tothe transmitting node that the packet was received and returns some typeof error correcting code. Indeed, the present inventors recognize thatfor a relatively short data payload DP, then a great deal of therelative power/energy consumption involved in the communication (i.e.,transmit, receipt, and acknowledgment) of that packet relates to thepacket preamble PR and header HR, that is, for a smaller data payloadDP, the packet preamble PR and header HR constitute a total greaterpercentage of the entirety of information in the packet and, hence, theylikewise constitute a total greater percentage of the power/energyconsumed in communicating the packet. The preferred embodiments,therefore, seek to reduce such power/energy consumption, as furtherdetailed below.

FIG. 3 illustrates an example of a communication packet PT_(PLC) forG3-PLC, an industry standard developed for powerline communications inan electricity grid. The G3-PLC packet PT_(PLC) includes the samegeneral segments of FIG. 2, including therefore a packet preamble PR, aheader HR (sometimes referred to as a frame control header, FCH), and adata payload DP. The packet preamble PR includes eight identical SyncPsymbols, where each such symbol is a so-called chirp signal, meaning asignal in which the frequency changes (e.g., increases for the SyncP) intime. After the eight SyncP symbols, the packet preamble PR concludeswith one and a half SyncM symbols, which SyncM is the negative of SyncP,so that the SyncM is also a chirp signal with a frequency increasing intime, but with a negative amplitude relative to the SyncP sysmbol. Ingeneral, the packet PT_(PLC) preamble PR is used for synchronization anddetection and provides a known sequence to facilitate automatic gaincontrol (AGC) adaptation. The PT_(PLC) header HR (or FCH) consists of anumber (e.g., 13) of FCH symbols, each comprising both an FCH segmentand an FCH cyclic prefix, separated from a preceding FCH symbol by aguard interval (GI). Also in FIG. 3, each FCH segment is shown with asubscript of 6, as a so-called super ROBO coding is involved in encodingwhat results in the 13 FCH symbols. Particularly, the informationencoded in header HR initially consists of a number of bits, where inthe example of a CENELEC header for IEEE 1901.2, the number of bitsequals 39 bits. These bits pass through a ½ convolutional encoder, whichthereby doubles the information to 78 bits. Repetition by 6 coding isthen applied to each of these 78 bits, meaning, for each bit, its valueof 1 or 0 is repeated 6 times, thereby creating a total of 468 (i.e.,78*6=468) bits; these bits are interleaved and then communicated acrossa total of 36 frequencies or tones, thereby resulting in 468/36=13 FCHsymbols, as shown in FIG. 3. On receipt of the header, therefore, thereceiving node N_(x) reverses the above, so as to eventually decode backto the original 39 bits. Further, the G3-PLC packet header HR containsthe control information required to demodulate the data payload. Lastly,the packet PT_(PLC) data payload DP includes any number N of datasymbols, also separated by guard intervals (GI).

FIG. 4 illustrates a flowchart of a preferred embodiment communicationmethod 100 for one or more of the nodes N_(x) from FIG. 1, which by wayof example is illustrated in connection with G3-PLC. Method 100commences with a step 110 where a node joins a session with anothernode. By way of example, therefore, node N₁ may join a session with nodeN₂, so that the two nodes may communicate data between them and also forpotentially one of the two nodes routing data to another distant node.In general, therefore, node N₁ communicates at least one packet PT_(PLC)to node N₂, so as to establish a communication session between the two,where a session is typically defined by an introductory packet sent by afirst node to a second node, and some form of acknowledgment response bythe second node back to the first node; indeed, further in this regard,PLC also supports a shorter ACK packet (or frame), which consists onlyof the preamble PR and the header HR and is sent by a receiving node soas to provide a verification to the sending node that the sending node'spacket was successfully received.

After step 110, method 100 continues with a determine channel quality(CQ) step 120. Channel quality CQ is intended in this document torepresent a measure of the ability for information to be accuratelycommunicated between the two nodes of the session, where one typicalmeasure would be signal-to-noise ratio (SNR). In this regard, step 120may be realized by the first transmitting node N₁ sending a request tothe second receiving node N₂ so that the latter can determine thechannel quality CQ based on known measures from a received packet. Instep 120, the second receiving node then reports this CQ measure back tothe first transmitting node, where the report may be in a separatecommunicated packet PT_(PLC).

After step 120, method 100 continues with a comparison step 130 in whicha session node, such as the transmitting node (e.g., N₁), determineswhether the channel quality CQ exceeds a threshold THR. If the channelquality CQ exceeds the threshold THR, then method 100 continues to step140; otherwise, then method 100 continues to step 150. The value of thethreshold THR may be established by one skilled in the art, given thetype of measure used from the channel quality CQ, the type ofcommunication, and other factors as ascertainable by the teachings ofthis document.

Note also that steps 120 and 130 may be achieved given an implicitrecognition from the packet data payload modulation scheme.Specifically, in some existing packet protocols, a system may make anadjustment to the modulation scheme of a packet data payload, based onchannel quality. For example, in various wireless and wirelinetechnologies, for example, for a poorer channel quality, BPSK is usedfor the data payload, while for a next improved channel quality, QPSK isused for the data payload, and for a next improved channel quality, 8PSKis used for the data payload; in such implementations, however, only thedata payload modulation scheme is adjusted, while the preamble andheader are rigidly specified and maintained irrespective of channelquality. Given the preceding, in systems where the data payloadmodulation schemes is changed based on channel quality, then steps 120and 130 may be realized by detecting the modulation scheme, or anindicator of the scheme, as a representation of the channel qualityrelative to a threshold, where, for example, step 130 may detect a BPSKdata payload which thereby corresponds to the channel quality notexceeding a threshold, whereas step 130 may detect a QPSK (or 8PSK) datapayload which thereby corresponds to the channel quality exceeding athreshold.

Step 140, having been reached because the channel quality CQ exceeds thethreshold THR, thereby represents that the channel quality is betterthan might be expected under default (or even worst case scenario)conditions. As a result, step 140 operates to reduce one or both of thepreamble PR length and the header HR coding; this action may beaccomplished in various manners, such as setting an indicator (e.g., aflag) that is in, or readable by, the nodes of the session so that, tothe extent they are capable of changing preamble and header lengths orformats, they will operate with the reduction of step 140. To this end,following step 140 is a step 160 in which any node in the sessionreached from step 140 will communicate per the threshold detection ofstep 130, and the reduction of step 140. Thus, whereas FIG. 3 representsa default packet PT_(PLC) for PLC communications, FIG. 5 illustrates analternative, lesser-energy consuming PLC packet indicated as PT′_(PLC).Again, packet PT′_(PLC) includes a packet preamble PR, a header HR, anda data payload DP, but in a preferred embodiment, alterations areimplemented in one or both of the preamble PR and header HR so as toreduce the energy required of the session nodes in communicating thepacket. In the example of FIG. 5, therefore, such energy reduction isachieved by reducing the eight identical SyncP symbols in the FIG. 3packet preamble PR to four symbols, indicated as SyncP′, whichpreferably are time-inverted SyncP symbols, meaning instead of frequencyincreasing chirp signals, each SyncP′ is a frequency decreasing chirpsignal and otherwise is a mirror-image of the rate of change infrequency relative to the SyncP symbols. By time-inverting in thismanner, the syncP′ symbols of FIG. 5 have a low cross correlation withthe syncP symbol in FIG. 3.

Also in the example of FIG. 5, additional energy reduction is achievedin the header HR by reducing the FIG. 3 repetition by 6 (i.e.,conventional super ROBO) coding in the header to repetition by 2. Thebenefits of such a reduction may again be illustrated using theabove-introduced example of the information encoded in header CENELECheader for IEEE 1901.2, where recall that 39 bits of information areencoded into the header. For FIG. 5, these bits again pass through a ½convolutional encoder, which thereby doubles the information to 78 bits.Here, however, repetition by 2 coding is then applied to each of these78 bits, meaning, for each bit, its value of 1 or 0 is repeated 2 times,thereby creating a total of 156 (i.e., 78*2=156) bits. Again, these bitsare interleaved and then communicated across a total of 36 frequenciesor tones, but with only a total of 156 bits (as compared to the 468giving rise to the FCH symbols in FIG. 3), then spreading those bitsacross the 36 tones can be accomplished in only 5 FCH symbols (i.e.,CEIL 156/36]=5, that is, rounding 156/36 up to the next integer), asshown in FIG. 5. Again on receipt of the header, therefore, thereceiving node N_(x) reverses the above, so as to eventually decode backto the original 39 bits, but here with much greater efficiency as only 5FCH symbols are received and consume energy in the decoding process.

Having described step 140 which is reached because the channel qualityCQ exceeds the threshold THR, step 150 represents the oppositeconclusion of step 130, that is, where the channel quality CQ does notexceed the threshold THR. In step 150, therefore, the preferredembodiment maintains the communication system (e.g., PLC) default orstandard-defined preamble PR length and header HR coding. Thus,communications proceed from the session nodes as again shown in step160, but now according to the default of step 150. Thus, as illustrated,such communications would follow the packet PT_(PLC) of FIG. 3, ratherthan the reduced energy packet PT′_(PLC) of FIG. 5.

After step 160, method 100 continues with a comparison step 170, whichis generally a wait state so that packet communications may continue pereither step 140 or step 150, until the session is interrupted. Thus, ifno session interruption occurs, then method 100 is shown to loop back tostep 160 so that communications can continue based on an earlierselection of either step 140 or step 150 for the session. Eventually,the session may be interrupted, such as by a receiving node sending backcontrol information indicating there was an error, multiple errors, orrepeated errors in a received communication(s), where such controlinformation may be way of a NACK communication or packet. Alternatively,the session may be interrupted by the transmitting node having a timeoutperiod expire in which it expects to receive an ACK packet and none isreceived, as may occur from packet drops as between the nodescommunicating in the session. In any event, if a session interruptionoccurs, then method 100 returns to step 110, in which case the abovemethodology again repeats.

FIG. 6 illustrates a partial flowchart of another preferred embodimentcommunication method 100′, as a modification of method 100 of FIG. 4 andagain, however, for one or more of the nodes N_(x) from FIG. 1 and inthe example of G3-PLC. Specifically, FIG. 6 illustrates alternativesteps 130 ₁ and 130 ₂ for step 130 in FIG. 4, whereby the channelquality CQ may be compared to multiple thresholds THR₁ and THR₂,respectively. In the same way as FIG. 4, if the channel quality CQ doesnot exceed any threshold, then again step 150 maintains a defaultpreamble PR length and header HR coding. However, if the channel qualityCQ exceeds a first threshold THR₁ as shown in step 130 ₁, then thechannel quality CQ is also compared to a second threshold THR₂ in step130 ₂, where such comparisons therefore will direct communications toeither a LEVEL ONE (step 140 ₁) reduction of preamble PR length andheader HR coding for an intermediate level of channel quality, or to aLEVEL TWO (step 140 ₂) reduction of preamble PR length and header HRcoding for an even better level of channel quality. For example, whereasstep 140 of FIG. 4 directed to a preamble PR with four SyncP′ symbolsand a header using repetition by 2, then in method 100′ such parametersmay apply to LEVEL ONE in step 140 ₁, whereas LEVEL TWO in step 140 ₂may further reduce the energy for packet communication by having norepetition in the header HR (and potentially reducing the preamble PR,as well). In any event, therefore, a preferred embodiment may use threeor more different levels of either preamble length or header coding,with reductions commensurate with the channel quality, thereby allowingreduced energy consumption when an improved channel quality is present.

Decoding by a receiving node in each preferred embodiment is consistentwith the above teachings. Thus, when a receiving node detects a packetwith a shortened preamble PR arising from an SNR that exceeds athreshold (i.e., shortened relative to the default preamble), then inone preferred embodiment, decoding of the header HR assumes the headerHR is also shortened, consistent with the shortened preamble PR. In analternative preferred embodiment, even if the receiving node detects apacket with a shortened preamble, the decoding recognizes thepossibility that the header HR may not necessarily also be shortened. Toaddress this contingency, the alternative preferred embodiment candecode the header HR both as a shortened header as well as thedefault-sized header. For example, in the instance illustrated by FIGS.3 and 5, the header HR may include 13 FCH symbols encoded by repetitionby 6 or 5 FCH symbols encoded by repetition by 2. In this case,therefore, if the preamble is short, the receiving node will receive andstore bits sufficient to encompass 5 FCH repetition by 2 symbols, decodethose bits under the assumption that this information is 5 such symbols,and then check the CRC; if the CRC passes, then the receiving node isthereby informed it has reached the end of the header HR by due to thepass. On the other hand, if the CRC check fails, then the receiving nodeaccumulates additional bits which, with the already-received bits aresufficient to encompass 13 FCH repetition by 6 symbols, and the entiretyof these bits are then decoded under the assumption that thisinformation is 13 such symbols.

While the preceding examples have been in the context of wireless (e.g.,PLC) communications, alternative preferred embodiments also contemplateFIGS. 4 and 6 applied to wireless communications. For example, IEEE802.15 specifies wireless personal area network (WPAN) standards andIEEE 802.15.4 specifies the physical layer and media access control forlow-rate wireless personal area networks (LR-WPANs). In this regard, inconnection with the optional O-QPSK modulation, the standard calls fordata at four different rates with four different spreading factors, alsoknown as Direct Sequence Spreading (DSSS). However, the PHY structurefor the packet requires that all four rates use the same preamble andstart frame delimiter (SFD) that together are considered asynchronization header (SHR), consisting of a 32-bit preamble and a16-bit SFD, for a total of 48 bits, and these 48 bits are spread by afactor of 32 for a total of 1,536 chips. Applying the preferredembodiment to this standard, however, provides an energy-reduced, lengthshortened, SHR, when channel quality is relatively high, as will be thecase when the data payload has a higher data rate, such as RM2 and RM3,while a higher energy consuming, longer SHR is used for lesser channelquality, as will be the case when the data payload has a lower datarate, such as RM0 and RM1. As an example, the shortened SHR may consistof only 24-bits of preamble and SFD, instead of the standard 48-bits ofSHR. Moreover, the partitioning of bits between the preamble and SFD maybe altered. In one example, the reduced 24 bits of SHR are partitionedbetween 8-bit preamble and an alternate 16-bit SFD that has goodcross-correlation properties with the original 16-bit SFD, or analternate example of the reduced 24-bit SHR are partitioned between 12bits of preamble and a 12-bit SFD that also has good cross-correlationproperties with the original 16-bit SFD.

Also recognized in the preferred embodiment is that in a network ofnodes, from a tree structure standpoint and message hopping from a rootnode down to the leaf node(s), different nodes may be wireline orwireless. Further, along certain paths, all the intermediate nodes maybe hybrid nodes, that is, they support both wireless and wireline. Inthis regard, therefore, a preferred embodiment methodology provides thateach intermediate node chooses a packet preamble or header thatminimizes energy consumption (i.e., either transmit, receive, or acombination of both), given the discerned channel quality, as well asthe transmit power and physical layer technology available to the node.Thus, the choice is made not just within the rate modes of OFDM andwithin the rate modes of O-QPSK separately, but instead between all theavailable rate modes, such as between FSK, OFDM, and O-QPSK as a singleset. Or, the set may be reduced with choices still available from withinit, so for example the set may include the higher rate modes of O-QPSK,with the alternative preambles described earlier. Thus, in someembodiments, the choice is between a given wireless standard or awireline standard from the perspective of minimizing total energyconsumption. In instances where there are multiple hops between the leafnode and the root node, and all the intermediate nodes are hybrid nodes,the intermediate communication link may be chosen based on the PHYtechnology that minimizes the energy consumption for successfulcommunication of the given packet size.

From the above, various embodiments provide numerous improvements topacket communication by providing a methodology that optimizes packetpreamble and/or header so as to reduce energy in communication of thepacket during a session. Such improvements are evident from the above,and also have been observed by the present inventors considering that,in a point to point communication link between two nodes, thetransmission time for a packet transfer is given by the time taken for apacket transmission, which necessarily includes the preamble and headeroverheads, and the time for an acknowledgement which also (e.g., forPLC) may include the preamble and header. Thus, the communication energyfor such packets is directly affected by the energy expended intransmitting, receiving, and decoding the information in the packet thatprecedes the data payload, and for short data payloads, therefore, arelatively larger amount of energy is consumed with respect to non-datapayload information. Such energy consumption is considerably undesirablefor certain types of nodes, particularly those operating on batterypower. Thus, the preferred embodiments improve on such considerations,with therefore various benefits over the prior art. Various aspects havebeen described, and still others will be ascertainable by one skilled inthe art from the present teachings. Given the preceding, therefore, oneskilled in the art should further appreciate that while some embodimentshave been described in detail, various substitutions, modifications oralterations can be made to the descriptions set forth above withoutdeparting from the inventive scope, as is defined by the followingclaims.

The invention claimed is:
 1. A method for transmitting information, themethod comprising: determining channel quality of a communicationchannel onto which the information is to be transmitted; based on thechannel quality, selecting a packet format for transmitting theinformation from one of a first packet format having a preamble, aheader having a first length, and a data payload and a second packetformat having the preamble, a header having a second length, and thedata payload, wherein the first length is greater than the secondlength; encoding the information into a packet based on the selectedpacket format; and transmitting the packet onto the communicationchannel.
 2. The method of claim 1, wherein the first length is based atleast partially on selecting a first level of bit repetition, andwherein the second length is based at least partially on selecting asecond level of bit repetition that differs from the first level of bitrepetition.
 3. The method of claim 2, wherein the first level of bitrepetition is 6 and the second level of bit repetition is
 2. 4. Themethod of claim 1, wherein the preamble has a third length for the firstpacket format, the preamble has a fourth length for the second packetformat, and the third length has greater than the fourth length.
 5. Themethod of claim 4, wherein the third length is based at least partiallyupon a first number of repeating chirp symbols, the fourth length isbased at least partially upon a second number of repeating chirpsymbols, the first and second numbers being different.
 6. The method ofclaim 5, wherein each chirp symbol in the second number of repeatingchirp symbols is a time-inversion of each chirp symbol in the firstnumber of repeating chirp symbols.
 7. The method of claim 1, whereintransmitting the packet onto the communication channel when the selectedpacket format is the second packet format requires less powerconsumption relative to transmitting the packet onto the communicationchannel when the selected packet format is the first packet format. 8.An electronic device comprising: a transmitter; a memory to storeinstructions and information to be transmitted using the transmitter;and a processor configured to execute the instructions to cause theelectronic device to: determine channel quality of a communicationchannel onto which information is to be transmitted; based on thechannel quality, select a packet format for transmitting the informationfrom one of a first packet format having a preamble, a header having afirst length, and a data payload and a second packet format having thepreamble, a header having a second length, and the data payload, whereinthe first length is greater than the second length; encode theinformation into a packet based on the selected packet format; andtransmit the packet onto the communication channel using thetransmitter.
 9. The electronic device of claim 8, wherein the firstlength is based at least partially on selecting a first level of bitrepetition, and wherein the second length is based at least partially onselecting a second level of bit repetition that differs from the firstlevel of bit repetition.
 10. The electronic device of claim 8, whereinthe preamble has a third length for the first packet format, thepreamble has a fourth length for the second packet format, and the thirdlength is greater than the fourth length.
 11. The electronic device ofclaim 10, wherein: the first length has a greater number of bits thanthe second length; and the third length has a greater number of bitsthan the fourth length.
 12. The electronic device of claim 10, whereinthe third length is based at least partially upon a first number ofrepeating chirp symbols, the fourth length is based at least partiallyupon a second number of repeating chirp symbols, the first and secondnumbers being different.
 13. The electronic device of claim 12, whereineach chirp symbol in the second number of repeating chirp symbols is atime-inversion of each chirp symbol in the first number of repeatingchirp symbols.
 14. The electronic device claim 8, wherein the packet,when transmitted onto the communication channel in the second packetformat, requires lower power consumption than when transmitted onto thecommunication channel in the first packet format.
 15. An electronicdevice comprising: a transmitter; a memory to store instructions andinformation to be transmitted using the transmitter; and a processorconfigured to execute the instructions to cause the electronic deviceto: determine channel quality of a communication channel onto whichinformation is to be transmitted; perform a first comparison thatcompares the channel quality to a first channel quality threshold;select a first packet format for transmitting the information when thefirst comparison indicates that the channel quality is less than thefirst channel quality threshold; perform a second comparison thatcompares the channel quality to a second channel quality threshold thatis greater than the first channel quality threshold when the firstcomparison indicates that the channel quality is greater than the firstchannel quality threshold; select a second packet format fortransmitting the information when the second comparison indicates thatthe channel quality is less than the second channel quality threshold;select a third packet format for transmitting the information when thesecond comparison indicates that the channel quality is greater than thesecond channel quality threshold; encode the information into a packetbased on the selected packet format; and transmit the packet onto thecommunication channel using the transmitter; wherein each of the first,second, and third packet formats includes a preamble portion, a headerportion, and a data payload portion, wherein the header portion of thefirst packet has a first length, the header portion of the second packethas a second length, and the header portion of the third packet has athird length, the first length being greater than the second length andthe second length being greater than the third length.
 16. Theelectronic device of claim 15, wherein: the first length is based atleast partially on selecting a first level of bit repetition; the secondlength is based at least partially on selecting a second level of bitrepetition; the third length is based at least partially on selecting athird level of bit repetition; the first level of bit repetition isgreater than the second level of bit repetition; and the second level ofbit repetition is greater than the greater than the third level of bitrepetition.
 17. The electronic device of claim 15, wherein: the preambleportion of the first packet format has a fourth length; the preambleportion of the second packet format has a fifth length; the preambleportion of the third packet format has a sixth length; the fourth lengthis greater than the fifth length; and the fifth length is greater thanthe sixth length.
 18. The electronic device of claim 17, wherein: thefourth length is based at least partially upon a first number ofrepeating chirp symbols; the fifth length is based at least partiallyupon a second number of repeating chirp symbols; the sixth length isbased at least partially upon a third number of repeating chirp symbols;the first number of repeating chirp symbols is greater than the secondnumber of repeating chirp symbols; and the second number of repeatingchirp symbols is greater than the third number of repeating chirpsymbols.
 19. The electronic device claim 15, wherein: transmitting thepacket when the selected packet format is the first packet formatrequires a first amount of power; transmitting the packet when theselected packet format is the second packet format requires a secondamount of power; transmitting the packet when the selected packet formatis the third packet format requires a third amount of power; the firstamount of power is greater than the second amount of power; and thesecond amount of power is greater than the third amount of power.